General tips on ID of Nudibranchs

[Deefstes]

Hi all, I'm hoping someone can point me towards a resource of sorts that can help with some general identification tips on Nudibranchs.

I come from a birdwatching background and I'm obsessed with identifying everything I see. I've learned to eat humble pie under water but I still try to make an effort.

Some fishes are reasonably easy to at least put into a family which makes it easier to narrow it down to species level. With Nudibranchs I'm still very much in the dark though. Sure, Flabellinas are quite a bit different from Chromodorids, but for the most part, when I see a Nudibranch I don't even know where to start.

There are some excellent websites that have helped me before such as Nudi Pixel: Nudibranch and Sea Slug Identification with Photographs, Seaslug Molluscs Opisthobranchs Nudibranchs and The Sea Slug Forum - Home Page but I have yet to find something that gives me a systematic approach to identifying nudis.

Any help?

 

[Vie]

... for the most part, when I see a Nudibranch I don't even know where to start.

The only consolation I can give is that eventually you'll pick it up. Just keep on diving, looking, reading and using any available resources. You'll start to notice the differences between the different families and genera, and the various characteristics of each; then it will be come much easier.

It took me a while to figure out that not all sea slugs are nudibranchs and that creature that looked (to me) like sea slugs could also be flatworms or juvenile sea cucumbers or cowries or velutinids, etc, etc...

Wait 'til you get into flatworms...

 

[Kupu]

My favorites for ID are Nudibranchs Encylopedia by Neville Coleman and Nudi Pixel. Between those two I can find ID for most, but not all, nudibranchs. If I have a photo, but no idea what species, I flip thru the Encyclopedia, putting bookmarks on the pages that contain a possible match. Then I go online and check out the Nudi Pixel photos, which usually gives me a better idea of the possible variations within a particular species. If I am still unsure, I go over to The Sea Slug Forum and read the fact sheets, which help by giving a bit more specific info.

I really enjoy the challenge of nudibranch ID, and agree with Vie that it does get easier with practice.

If you are serious about ID, it probably makes sense to purchase a book or two. Scanning thru web pages with no sense of direction can take ages to find what you need, flipping thru a book and marking likely matches might be more productive.

Hope that is helpful, I always have fun when I encounter another slug addict on the dive boat.

 

[CompuDude]

I agree, books help a lot.

You'll start to get a feel for general body shapes to narrow the search, otherwise, yes, it just takes experience to start picking out the fine details. The better books will also point out differences between similar species, in some cases.

I'd specifically look for the books by David Behrens (and other contributors):

Indo-Pacific Nudibranchs and Sea Slugs
Nudibranch Behavior
Eastern Pacific Nudibranchs

Helmut Debelius' "Nudibranchs of the World" is also quite good (if expensive), but doesn't include much text to accompany the photos.

Most can be found on Amazon or the Sea Challengers website.

 

[vladimir]

My favorites for ID are Nudibranchs Encylopedia by Neville Coleman

As an aside, I have had the pleasure of spending a couple of weeks in PNG with Neville. He is an interesting character who can spin a story with the best of them, and quite a nice guy as well. He has a nudibranch species named after him, Chromodoris colemani.

 

[Vie]

He has a nudibranch species named after him, Chromodoris colemani.

There are quite a few creatures named after Neville. The aeolid Phyllodesmium colemani and the pygmy seahorse Hippocampus colemani to name just a couple more.

These guys just keep naming critters after each other. There are a whole bunch named after Rudman, Kuiter, Debelius, Behrens etc.

I agree that ID books are a great starting point but one thing to note is that the information (names, for example) and change very quickly as unnamed species are finally studied and published, genera are reorganized, etc. The good thing about websites such as Bill Rudman's is that it can be updated quickly.